Geophysical surveys of this mysterious oval mound suggest it was originally two Bronze Age round barrows, aligned SE-NW. They're apparently the nearest barrows to Gorsey Bigbury henge. Curiously the results showed their ditches had little causeways, and the causeways faced each other (imagine a C and a backwards C) - the barrows were only a metre apart. It makes you wonder about the story behind their design and who were buried there.
(info from Jodie Lewis's article in Proc Univ Brist Spel Soc 2003 vol23)